Polly Stenham is just 20 years old and her debut play is a youthful work. Structurally it’s a little baggy; but it's remarkably confident and exuberantly theatrical. Crammed with startling stage images, ferocious cruelty and pitch-black humour, it is insolent, audacious, witty and wise — and Jeremy Herrin’s sparky production, with an excellent cast led by Lindsay Duncan, matches its swagger.

The Royal Court’s artistic director, Dominic Cooke, has declared his intention to present more work located in a middle-class milieu, and That Face fits the bill. It’s no soft option, chillingly exposing the spiritual bankruptcy at the heart and hearth of many a well-to-do home.

At her expensive boarding school, Mia and her friend Izzy put a fellow pupil through a nasty initiation ceremony that goes badly wrong. Back at the family flat in London, Mia’s elder brother Henry, an aspiring artist, looks after their febrile, fragile mother Martha amid a chaos of prescription drugs, drink and emotional dependency. When Martha’s ex-husband, Hugh, returns from Hong Kong to help clean up the mess, all-out war breaks out among the fractured family.

Stenham intelligently evokes the close relationship between neglect and active abuse: Hugh’s paternal absenteeism is as damaging as Martha’s histrionics. Materially, Mia and Henry are well provided for; when it comes to stability and love, they are dangerously malnourished.

Effectively parentless, Mia becomes a ticking bomb of vengeance and misery, while Henry is father, lover, boy-child and confidant to Martha. He is tearing himself to pieces to satisfy his mother’s demands — a process mirrored in her ripping up of every garment he possesses when he spends a night not in her bed, but in Izzy’s. Like Nicky and Florence Lancaster in Coward’s The Vortex, they are bound together by an almost incestuous intensity. And Stenham smartly nails the way in which Martha’s anxiety over her own fading star devours her children’s potential.

It’s a powerful study of emotional deprivation, no less forceful because its setting is well-heeled metropolis rather than sink estate.

Herrin’s production mines the grit in the gloss. Julian Wadham’s plummy Hugh regards his devastated family with detached despair, while Lindsay Duncan as Martha flirts, play-acts and poses, switching from little girl to matriarch to femme fatale. A bohemian beauty in decline, she is magnetic yet disgustingly narcissistic, seeing her children only as products of herself — her son as her own dazzling reflection, her daughter an inconvenient excretion.

Felicity Jones as Mia mingles sassy bravado and a sadistic streak with poignant bewilderment, and Matt Smith’s Henry is a desperate prisoner in his mother’s madhouse, forbidden to cross the threshold into manhood. He ends the play sobbing, urine-soaked, wearing Martha’s silk slip and jewellery, while Jones’s Mia tries to offer comfort.

It’s not just Mia and Henry who are children in crisis; the play is astutely suggestive of a society in which the siren song of youth is so seductive that even adults — and parents — refuse to grow up. A fizzing, glittering fireworks display of fresh talent.

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